Rotary propeller and the like device



Jan. 9, 1940. A. J. DEKKEIR 2,186,064

ROTARY PROPELLER AND THE LIKE DEVICE filed May 19, 193'! 2' She'ets-Shet 1 1940- A. J. DEKKER 2,186,064

ROTARY PROPELLERAND THE LIKE DEVICE Filed Ma 19, 1937 2'Sheets- Sheet 2 Patented Jan. 9,

The present invention relates" to rotary [propeller devices having blades orfthe like by means f whichenergy is given to'a medicine! obtained from ajmediu' c V Propeller devices can be divided into two distinctive principal groups:

I. Screw pr0peZ'Zers.In these one or more blades move, causing or obtaining pressure on or from themedium in an axial directionforming a rather small angleof incidence: with the direc+ tion of the'plane or planes in'whichjthe bladeslie.

' II. C'yloidal propeZZers.--Inthese one or more blades or paddles -move, causingforYobtaining l5 pressure on or from the'medium, infa' direction forming an angle of incidence of 90"with" the plane or planes in which the blades or paddles d v. v v

' In these two kinds of constructions the renew-- in vourable characteristics are shown with reasing axial velocit 7 -(a). as transmitters of energy to ith emedium they pcssessless reaction pressure}. f j (b) as receivers of energy from the medium theyexert lessv pressure onthe'mediiirng This can be x la d, orjbqthgpa e b th fact that the transmitted or 'recei'vedenergy-depends on the so-called slip r me two kinds of propellers, and this' slip dec h increasjm r nubgrtsofie behmd theemr,icn esciyorw nner? amberb: the sail sl'iaped bladesarefitte as hub part revolve's in th preceding onej 'prefrab speed a'z ia m ""mafi-n 4 undistiirbd-,;1th xv stream pf; aemgemi I 2, 1ss,oc4 RQPEL R' ND THE AdriaaniJanDckkerj Leiden, Netherlands, as-

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with ccnsequentflla'ck of control over the 'aircraft. bestresult is obtained' when the second hub part revolves more slowly than' thefirst, and when the mutual distance between the blades of two successive hub parts of one groupimeas- 5 ured from'the rear edge of a front bladeto' the leadingfledg e of a rear blade) is from the minimum practical working clearance up to" 20%' of the total d'ajineter of the propeller, when measuredfro'rn the tip of the'blades. c

' The invention will'now be described by wayof example with reference to fthe accompanying drawingsfwhichshow, by way of example, one constructional form of theinventicnf j Fig: l'is afront view partly in section' accord- 16 ing to the line 1-1 of Fig.

Fig. Z isaside view and I H V Figs. 3, '4 and" 5 "are respectively"sections of a blade' according to the lines El III; and Ia- 1 Fig; 6 is cross section 'elevationfshowingthe drive and Figs. ,7 and 8 are diagraminatic views Figs; 9 and 10 arefdiagramn aticfplan views showing slip [streams for j' respective single" and 25 d u e rbp e units'. if The rather mcks am m r p n b' a is n two $1 $1123fi wan ed i efpt te i i e h enib t e y ov ded fe r g eiebezi iv i 0 'fi-"betweli the m v, H v v rotation r m y dcregs tffth Th1 of the hub the blades are direction dfi rotation '"ag c ar'e 'ex is driven with a rotational speed which is 66% of the rotational speed of the front section 2.

It is thought that the reason why the reaction moment is obviated when the rear blades are rotated slower than the front blades is that the front blades direct the air reawardly and in their direction, that is, the air stream is directed to some extent helically and this adds to the resistance which the rear blades encounter and thus increases the reaction moment to an amount opposite and equal or substantially equal to the reaction moment of the more rapidly rotating front blades.

The driving mechanism is shown in Figs. 6 to 8 and consists of the engine shaft 5 driving an epicyclic gear consisting of the toothed sun wheel 6, three planets I on a carrier 8, and an internally toothed annulus 9 fixed on the casing Hi. The carrier 8 is fixed n,or formed on, a shaft I l which carries the front hub part 2. The shaft II also carries a sun wheel l2 of a second epicyolic gear including the three pairs of planet wheels l3 (see especially Fig. 8). The iimer wheel of each pair meshes'with the sun wheel I! and its fellow while the latter meshes with an internally toothed annulus l4 fixed in the casing Ill. The planets'i3 are mounted on a carrier l5 fixed or formed on a hollow sleeve or shaft l6 which carries the rear hub part 3 and surrounds the shaft II and is mounted to rotate on ball bearing IT, a further ball bearing 3- being located between the shaft I l and the member I! of the rear hub part 3, and a further ball bearing 20 being located between shaft II and carrier l5. It will be seen that with this arrangementthe front hub' part 2 will be rotated in the same direction as the engine shaft 5 while, owing to the planet pairs I3, the sleeve l6 which carries the rear hub part 3 will be rotated in the opposite direction. The gearing may, for example, be such that the rear hub part 3 makes 66 revolutions for every 100 revolutions of the front section, the opposite directions of rotation being indicated by the arrows shown in Fig. 2.

It will be seen that the blades 4 have substantially the shape of a fore-and-aft sail if the front edge of the blade is considered as the mast, the end as the gig and the tangent plane at the hub as the gafl to which the sail is attached, the blade being curved in the manner of a sail in two directions at right angles .to each other, that is, parallel to the mast and parallel to the gig with the greatest curvature near the mast and gig.

Just as in the case of sailing where the gig makes a smaller angle with the axis ofthe ship than the gafi, the chord of the end or tip of the blade makes a smaller angle with the axis of the propeller device than the chord of the root of the blade (see Figs. 3 to 5).

The blade is fixed to the hub part in such manner that during rotation without axial motion the particles of the medium impinge on the blade at an angle of about 70, which can be compared to sailing with half wind or close to the wind.

With increasing axial velocity and with constant rotational velocity the angle at which the particles of the medium impinge on the blade decreases. This can be compared to sailing close to the wind, when, as is well known, the tractive power or propelling force of the sail increases as the angle between the incoming wind and the reached at an angle of about 6. The equivalent maximum effect will only be attained by the propeller device in accordance with the present invention when the axial velocity amounts to fully twice the rotational linear velocity, the latter being measured at the blade end'or tip. Hence the tractive power of propelling force of the propeller device in accordance with the invention will increase till this velocity is attained.

Moreover, increasing the axial velocity, while the rotation velocity remains constant, causes the force with which the particles of the medium impinge upon the blade to increase, and thus the tractive power or propelling force also increases, just as in the case of sailing close to the wind the tractive power or propelling force of the sail increases in proportion to the velocity of the wind.

This increase in the tractive power or propelling force due to the increase of the axial velocity and the consequent pressure increase of the particles of the medium will only stop when the particles of the medium impinge upon the blade at an angle considerably less than 6. Only when, by a further increase of the axial velocity, these particles travel in the same direction with respect to the blade as the chord of the blade, will the tractivepower not show any further increase.

In order to obtain a proper sail effect the blades have been given a large surface. Because of this large surface the rotational velocity can be considerably less than that of other existing propellers. In this way an almost noiseless working is obtained, but at the same time the reaction torque is increased, which is a disadvantage.

This disadvantage is avoided or mitigated by rotating the hub parts 2 and 3 in opposite directions as above described. A further disadvantage which is obviated by having a rear hub part 3 rotating in the opposite direction, is that of a diffused or outwardly directed slip stream with reference to the axis of rotation. It has been foundthat such a divergent slip stream, as illustrated in Fig. 9, was given by a propeller device having only one hub part such as 2 with sail shaped blades thereon, as above described.

Such a divergent slip stream resulted in lack of.

air pressure on the elevators and rudder of an aircraft and caused an extreme difliculty in the control of the aircraft. Contrary to normal expectation, the rear contrarotating part 3,cor-- rectsthe slip stream, as illustrated in Fig. 10, and thus gives a slip stream which is flrm" and undisturbed and which is directed substantially straight back, generally in parallel directions ondifferent sides of the hub part, instead of substantially divergently as witha single propeller having the sail shaped blades.

What I claim is: l. A rotary propeller device comprising a plurality of hub parts placed one behind each other,

.allel directions on different sides of the hub parts. sail. decreases until the maximum effect is 2. A rotary propeller device comprising a plurality ofhub parts placed one behind the other, a plurality of blades on said hub parts, the blades areaoea having a concave pressure or medium-engaging side curved in a direction substantially parallel to the leading edge of the blade and also in a direction at right angles to said first direction, the chords of the blade sections making angles of about between 5to40with a plane containing the axis of rotation of said hub parts, and means for rotating alternate hub parts in opposite directions with the rear part, rotating slower than the front part so that the resulting reaction torque is substantially zero and the slip stream is di-' rected substantially straight to the rear without substantial spreading, the average distance between the rear edges of the blades on the leading hub part being from the minimum working clearance to 20% of the wing tip diameter.

' 3. A rotary propeller device comprising a plurality of hub parts placed one behind the other, a plurality of blades on said hub parts, the blades having a concave pressure or medium-engaging side curved both radially and axially with reference to the axis of rotation of the hub parts and the curvatures being respectively greatest in the region of the outer edge and the leading edgeof the blade and the chords .of the blade sections being inclined at right angles between 5 and 40 with reference to the planescontaining the axis of revolution of the hub parts and the blades being inclined radially with reference to the axis of rotation so that said medium-engaging side makes an angle less than 90 with a plane tangent to the hub part, and means for rotating alternate hub parts in opposite directions with the rear part rotating slower than the front part so that the resultant reaction torque-is substantially zero and the slip stream is directed substantially 'straight to the rear without substantial spreading, the average distance between the rear edges of the blades on the leading hub part being from the minimum working clearance to 20% of the wing tip diameter.

4. A rotary propeller device comprising a plurality of hub parts placed'one behind each other, a plurality of blades on each hub part, the blades being curved in two directions like sails and the chords of the blade sections making angles between 5 and 40 with a plane containing the axis of rotation of said hub parts, and means for rotating alternate hub parts in opposite directions with the rear hub part rotating slower than the front hub part so that the reaction moment,

of the different parts amounts practically to zero, and whereby the slip stream is relatively undisturbed and is directed substantially straight to the rear.

' 5. A rotary propeller device comprising a front hub part and a rear co-axial hub part which constitute a relatively thick hub of streamline form, each hub part having a plurality of blades thereon, the blades having a concave pressure or medium-engaging side curved in a direction substantially parallel to the leading edge of the blade and also in a direction at right angles to the said first direction and the chords of the "blade sections being inclined at angles between 5 to 40 to planes containing the axis of tota tion and the blades of the front section being inclined oppositely to those of the rear part, epicyclic gear means for rotating the front hub part, and further epicyclic gear means for rotating said rear hub part inthe opposite direction at about the number of revolutions of the front part, so that-the reaction'mement of the device is about zero and whereby a relatively undisturbed slip stream directed substantially to the rear is produced, the axial distance between the rear edge of'the front blades and the leading edge of the rear blades measured at the roots" of the blades being from 5% to 10% of the wing tip diameter.

6. A rotary propeller device comprising a plurality of hub parts placed one behind each other, a plurality of blades .on each hub part, the blades on each hubpart being curved like sails in two directions mutually at right angles and the chord of any blade section making an angle which is not more than 40 and is'not less than 5 with a plane containing the axis of rotation of said hub parts, and means for rotating alternate hub parts in opposite directions, so that the reaction moment of the different parts amounts practically to zero, and the slip stream is directed substantially to the rear generally in paralleldirections on different sides of the hub parts.

7.-A rotary propeller device comprising a plurality of hub parts placed one behind the other, a plurality of blades on each said hub parts, the blades on each hub part showing in cross-sections on any cylindrical surface co-axial with the axis of rotation as well as in cross-sections on any surface normal to the axis of rotation a shape the first said blade-cross-sections making angles of between 5 and 40 with a plane containing the axis of rotation of said hub parts, and the distance between the leading and rear edges of the blades of successive hub parts being from the minimum working clearance up to about 20% of the total diameter of the propeller, and means for rotating alternate hub parts in opposite directions.

8. An air-craft propeller comprising two co-axial hub parts constituting a substantially continuous streamline hub, a plurality of blades on each hub part, and means for rbtating the hub parts in opposite directions, the blades'on both hub parts showing on cylindrical cutting-surfaces coaxial with the axis of the hub parts cross sections similar to those of lifting airfoils and showing also on cutting-planes normal to said axis cross sections having each a-concave' pressure side, thechords of any of the'first said blade cross-sections making an angle of less than 40 but not less than 5 to said axis of rotation, the inclination of the blades on the respective hub parts being in mutually opposite senses, and the axial distance between the adjacent edges of the respective hub-part blades being from the minimum working clearance to 2 0% of the blade-tip diameter. 

